1. Field of the Invention
This application relates to the field of speed-responsive engaging devices for hydrodynamic devices.
2. Prior Art
It is known in the prior art to provide lock-up clutches for hydrodynamic devices. More particularly, copending applications, Ser. No. 620,461 filed Oct. 7, 1975 and Ser. No. 700,998 filed June 29, 1976 of common assignee provide clutch mechanisms for hydrodynamic devices having a shoe assembly engaged by centrifugal force and, in addition, engaged by a wedging effect of cam surfaces, and such clutch devices lock together the impeller and turbine elements to improve efficiency by eliminating slippage. It has been recognized that the structures of the aforementioned applications as well as the device to be described herein provide a solution to the problem of lock-up clutches to provide a lock-up clutch which disengages during torque impulses or torque reversals to provide smooth, shockless operation and eliminate torsional vibrations.
These previous solutions to the torque converter clutch problem, although workable and dramatic improvements over those known prior, have a somewhat sensitive characteristic which can be vastly improved. This identified need for improvement is in the area of engagement between the shoe assemblies and the cam itself. The previous solutions had a sliding engagement between the shoe assemblies and the cam surface. This type of construction induces a certain amount of frictional resistance to movement of the shoe assemblies along the cam surface. The ideal shoe assembly in a clutch environment of the type disclosed in the foregoing applications would have no frictional resistance to the movement of the shoe assemblies upon the cam surface.